Multimode (MM) fibers that operate at the wavelength range centered around 850 nm are known. The bandwidth (BW) of these multimode (MM) fibers is limited mostly by inter-modal chromatic dispersion. To minimize the inter-modal chromatic dispersion, MM fibers are designed with graded index α-profiles. Current high bandwidth (greater than 1 GHz·Km) optical fibers are optimized for use at 850 nm. Some of these MM fibers also have a second operating window, with much lower BW (<1 GHz·km) centered at 1300 nm.
VCSELs (vertical cavity surface-emitting lasers) being developed for wavelengths greater than 900 nm for high speed operation and their use provide significant advantages over the 850 nm VCSELS. VCSELs that operate above about 900 nm and below 1200 nm are now feasible. While these VCSELs are being proposed for high speed applications in the 900 nm-1200 nm wavelength range, optical fibers that are optimized to operate well in multiple wavelengths so that they can be used with 850 nm VCSELs and also with VCSELs that operate above about 900 nm and below 1200 nm are not available.
Although multimode fibers that are optimized for peak modal bandwidth at a wavelength near 850 nm can transmit at longer wavelengths, they exhibit low bandwidth in the 900 nm-1200 nm range, effectively limiting the system reach when such fibers are utilized with VCSELs being developed for wavelengths greater than 900 nm for high speed operations. On the other hand existing multimode fibers that have high bandwidth in a broad wavelength range are very difficult or impossible to make due to inter-modal chromatic dispersion because of material dispersion limitation.